BCE Inc. won big in a five-day promotional standoff between Canada’s largest wireless carriers in the fourth quarter, reporting its best wireless performance in 15 years thanks to high consumer demand for unprecedented data deals.

Bell added 175,204 wireless subscribers on contract in the three months ended Dec. 31, up 56 per cent from the same period in 2016, the company said Thursday. Telus Corp. said it added 121,000 wireless customers in the same period, up 39 per cent for its strongest results in five years. Rogers Communications Inc. added only 72,000 customers.

The Montreal and Vancouver-based telecoms credited the gains to successful responses to the aggressive holiday promotions that offered 10 gigabytes of data for $60 per month. Rogers, which triggered the deals, blamed its lower numbers on a computer glitch it said it has since fixed. The steep holiday discounts were widely seen as a response to Shaw Communications Inc.’s Freedom Mobile, which introduced similar plans for iPhones in November, even though Rogers insisted its move was unrelated.

The results from Bell and Telus easily topped analysts’ expectations and wrapped a banner 2017 for the Big Three communications giants, which collectively added 305,000 more wireless subscribers than in 2016 despite increased competition from Shaw in B.C., Alberta and Ontario.

But some analysts questioned the strategy behind steeply discounting prices to match Freedom’s offering – a move that could dampen revenue growth if customers come to expect lower prices.

“Why would incumbent wireless providers re-price their products to a level that makes it more clear to more people that they’re overpriced compared to new entrant,” Desjardins analyst Maher Yaghi said on a conference call with Telus executives.

Telus chief executive Darren Entwistle wouldn’t comment directly, but said Telus responded accordingly to the deals. He credited its customer service and fast network for its strong performance. Telus’ churn rate, the proportion of subscribers leaving for competitors in any given period, remained the lowest in the industry at 0.99 per cent. It would’ve been lower, but spiked during the rush for deals, Entwistle said.

“I’m kind of grumpy cause it wrecked our average for 2017, I wanted to be below 0.90,” he said.

The industry needs to be mindful of rate plan competition, Entwistle added. He noted heavy data use requires high capital investment in spectrum deployment.

“The rate plan discounts at the (average revenue per user) level frequently are not overcome by the volumes that get generated and can be net dilutive to the overall economics of the industry,” Entwistle said. “It’s important to be cognisant of that.”

Still, Telus’ average revenue per user grew 1.6 per cent to $67.27. Bell’s grew 2.4 per cent to $68.27. Bell chief executive George Cope told analysts he expects high mobile data usage, particularly when it comes to video, will continue to drive revenue growth.

Analysts were surprised by how many subscribers Bell won during the five-day blitz.

“We do not believe anyone had anticipated this magnitude of subscriber outperformance,” Barclays analyst Phillip Huang wrote to clients about Bell, noting it appeared to take significant market share during the promotions responded to Shaw.

While Shaw’s network lags behind the Big Three, analysts believe it could eventually start to chip away at their market share. They each hold about 30 per cent of Canada’s roughly 31 million wireless subscriptions.

In a conference call with analysts, Bell CEO George Cope emphasized Bell’s network speed and quality for the strongest results he said he has ever reported, citing Bell’s network advantage over Rogers, its top competitor.

“We think it’s just making a significant difference for us in growth,” Cope said.

Earlier this week, OpenSignal reported that Telus had the fastest network with Bell in second place and Rogers in third, based on 405 million speed measurements taken in the fourth quarter of 2017.

Overall, Bell’s financial results were in line with analysts’ expectations. It increased its dividend 5.2 per cent and reported adjusted profit of $684 million, up 2.5 per cent from the same period last year. Its media results were slightly below expectations given soft advertising revenue and higher content costs.

Bell’s wireless gains were largely independent from the expected shift of 230,000 customers to Bell from Rogers after Bell won the contract to provide mobile services to the federal government. Only 9,000 customers have migrated so far.

Bell beat expectations when it came to wireline subscribers. It added 27,000 internet customers and 7,000 television customers, improvements from the previous year. It lost 74,000 telephone subscribers, down from a loss of 100,000 in 2016.

Telus reported adjusted profit of $328 million, up 3.8 per cent from this period last year. It added 21,000 internet customers and 14,000 television customers, a dip from 2016. Landline losses slowed to 14,000 from 22,000 losses in the same period last year.

Both Bell and Telus credited investments in fibre-to-the-premises connections for success in their wireline businesses. Bell is accelerating its fibre build in Toronto and in Southern Ontario. Telus says it will have completed more than 50 per cent of its fibre build by the end of 2018.